Emission-free exhaust pipe joint and clamp therefor

ABSTRACT

The joint of the invention comprises exhaust pipes formed with beaded ends providing abutting flange-like surfaces that are axially forced together by a clamp applying wedging forces on the external beads. Modified forms of the joint have pilot extensions on one pipe of the joined pair, the bead on this one pipe in each case being spaced from the free end of the pipe. The pilot extension is telescoped within the other pipe bringing the beads together side by side and the clamp is engaged over both beads. In some joints, such as those formed in pipes made of a tough metal, a gasket may be inserted between the beaded ends. The clamp for the joints is one which has a concave groove engaging over the pair of beads to apply the axial force by the wedging action produced when the clamp is constricted. The preferred clamp is made in two halves which have a hinged connection of great simplicity comprising merely a rectangular bight formed on one end of one half and a tongue formed on one end of the second half. The tongue lies in the bight and cannot move laterally because of the self-centering action produced when the clamp is engaged on the beads. The other end of each half comprises a tongue with perforations aligned to receive a bolt and nut to enable the halves to be clamped together, pivoting with respect to one another on the hinged connection.

United States Patent [191 Stade et al.

[ 1 Jan. 29, 1974 EMISSION-FREE EXHAUST PIPE JOINT AND CLAMP THEREFOR[76] Inventors: Bertil Stade, 480 Kngllwood Drive,

Wood Dale, 111. 60191; Edward Hoglund, 1020 Lois Avenue, Park Ridge,111. 60068 22 Filed: Mar. 20, 1972 21 App1.No.: 236,364

Related U.S. Application Data [63] Continuation-impart of Ser. No.142,977, May 13,

1971, abandoned.

[52] U.S. CI 285/367, 285/410, 285/423 [51] Int. Cl. F16] 17/00 [58]Field of Search... 285/233, 365, 366, 367, 407, 285/408, 409, 410, 424,419, 373, 420, 283,

423; 24/284, 285, 125 K, 135 K, 249 LS 9 Primary Examiner-Dave W. ArolaABSTRACT The joint of the invention comprises exhaust pipes formed withbeaded ends providing abutting flangelike surfaces that are axiallyforced together by a clamp applying wedging forces on the externalbeads. Modified forms of the joint have pilot extensions on one pipe ofthe joined pair, the bead on this one pipe in each case being spacedfrom the free end of the pipe. The pilot extension is telescoped withinthe other pipe bringing the beads together side by side and the clamp isengaged over both beads. In some joints, such as those formed in pipesmade of a tough metal, a gasket may be inserted between the beaded ends.

The clamp for the joints is one which has a concave groove engaging overthe pair of beads to apply the axial force by the wedging actionproduced when the clamp is constricted. The preferred clamp is made intwo halves which have a hinged connection of great simplicity comprisingmerely a rectangular bight formed on one end of one half and a tongueformed on one end of the second half. The tongue lies in the bight andcannot move laterally because of the self-centering action produced whenthe clamp is engaged on the beads. The other end of each half comprisesa tongue with perforations aligned to receive a bolt and nut to enablethe halves to be clamped together, pivoting with respect to one anotheron the hinged connection.

11 Claims, 8 Drawing Figures sum 3 or 5 PATENTEDJAH 29 mm FIG.8

EMISSION-FREE EXHAUST PIPE JOINT AND CLAMP THEREFOR CROSS-REFERENCE TORELATED APPLICATION This application is a continuation-in-part of ourcopending US. application Ser. No. 142,977 filed on May 13, 197i and nowabandoned.

BACKGROUND OF THE INVENTION The invention herein relates to pipe jointsand clamps therefor and more particularly is concerned with a pipe jointand clamp therefor which is intended to be emission-free.

The internal combustion engine has been singled out as one of thegreatest sources of pollution today and on this account it has beenexamined carefully in every respect by governmental agencies fordeficiencies aside from the exhaust fumes which it emits. Additionally,automobile and truck manufacturers have become more sensitive to thewell-being of the passengers and drivers of the vehicles that areproduced to an extent where such manufacturers themselves havescrutinized the construction and operation of their own engines forfaults.

The invention herein is concerned with improvements in the exhaustsystems of vehicles motivated by internal combustion engines. The normallocation of an engine is in the front of the vehicle and this requiresthat the exhaust fumes from the engine be vented at the rear of thevehicle. Rear-engined and mid-engined vehicles have the same problemsbut to a lesser extent. The problem is to transport the exhaust fumes tothe tailpipe without loss of emission between the engine exhaustmanifold or manifolds and the tailpipe. The ordinary exhaust system hasa muffler which is interposed between the tailpipe and the exhaustmanifold. High powered vehicles have two exhaust systems from therespective groups of four cylinders of thecommon V-8 engine with amufflerand often a resonator in addition in each system.

It is obvious that an exhaust system which includes at least one mufflerand pipes between the muffler and engine and between the muffler and therear end of the vehicle can be made in a unitary assembly with thejoints permanently welded together. Such an exhaust system will beemission-free between the engine and the tailpipe vent. This wouldclearly prevent leaking exhaust fumes from entering the passengercompartment. Such a system would be unsatisfactory from two standpoints.In the first place it would be difficult to repair and replace and inthe second place it would be very expensive to replace. No exhaustsystem in commercially produced vehicles today is corrosion-proof.Accordingly it is expected that during the ordinary life of a vehiclethe muffler and perhaps the other pipes will at some time have to bereplaced.

The problems with known exhaust systems have not been satisfactorilysolved, so far as is known. The joints in such systems are notemission-free and this may be due either to the construction of thejoints or the construction of the pipe clamps used with such joints orboth. Presently known joints comprise telescoped lengths of pipe held insuch telescoped condition by means of constricting pipe clamps. Pipeclamps known apply considerable constricting force to squeeze the outerpipe against the inner pipe of the telescoped joint. These clampsliterally neck the outer pipe against the inner pipe, but in doing so,the outer pipe generally corrugates and the exhaust fumes escape throughthe corrugations.

In any event, present joints are not reliably emission free.

The invention herein is directed to structure which solves the aboveproblems. The invention comprises a joint and a pipe clamp for use withthe joint and the combination of both.

In the construction of pipe clamps another problem arises. Modern highspeed mass production has spawned a type of worker who must be providedwith tools and assembly jobs which require no exercise of judgement.Parts must go together in a fool-proof manner and be constructed toforgive bad performance by the worker. To be specific, in the case of apipe clamp, if there are two bolts which must be taken up in order tosecure the pipe clamp to a joint, it cannot be ex-' pected of suchworkman that he will carefully apply torque to each bolt alternatelyback and forth in order to constrict the clamp evenly. Thus it isabsolutely essential that the pipe clamp have only one bolt to be takenup and in so doing the workman must secure the clamp for its maximumutility and efficiency.

Prior clamps which have a single bolt take-up have not been able toapply even compression around their circumferences with resulting lossof efficiency.

The invention herein solves the problems which were inherent in priorpipe clamps that used a single bolt for take-up.

Three examples of prior art conduit joints and clamps are disclosed inthe following United States Patents:

Day 71 L946 Houghton, ct al. 2,548,216 Class 285-l29 Whitcornb 3,l 5 l.373 Class 24-279 In many applications the joint and clamp of theinvention have achieved an emission-free clamped joint without the useof gaskets. However in some applications where the pipes are made of atough metal, e.g., stainless steel, which is hard to form such that thebeaded ends are not substantially uniform in shape, a gasket may beemployed in the joint of the present invention between the beaded endsof the pipes.

SUMMARY OF THE INVENTION According to the invention, the joint forexhaust pipes is achieved by providing a rolled end on each pipe, therolled ends being butted face to face and presenting a pair ofcircumferential ring-like beads side by side to the pipe clamp. The pipeclamp for such joint has a band or pair of bands with a configurationwhich is arcuate in cross section or V-shaped and is encircled aroundthe joint with the beads engaged by the inside of the band or bands.Constricting the clamp by taking up on the bolt or bolts holding sametogether applies a wedging force of a substantial amount on therespective beads forcing them together axially and this provides anextremely tight joint. The joint is easily taken apart and the partsreplaced. The clamp does no damage to the pipes.

A preferred form of joint has in addition an extension on one of thepipes which telescopes within the other pipe, the rolled bead on thepipe with the extension being spaced from its end.

The pipe clamp of the invention has a pair of bands which include asimple bight on the end of one band and a flat radial extension on oneend of the other band. These two ends engage within one another and willnot separate laterally because the cooperation between the arcuategroove of the bands and the beads keep the bands perfectly aligned withone another. The opposite ends of both bands have cooperatingperforations for reception of a bolt and nut. Taking up on the bolt andnut will constrict the bands cooperatively upon the adjacent beadformations and wedgingly force them together axially to provide a tightconnection.

If desired, a gasket may be interposed between the rolled bead ends ofthe pipes in the pipe joint.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view withportions broken away showing the joint of the invention and a pipe clampconstructed in accordance with the invention;

FIG. 2 is a top plan view of the same with portions broken away;

FIG. 3 is a sectional view taken generally along the line 33 of FIG. 2and in the direction indicated;

FIG. 4 is a fragmentary sectional view taken generally along the line4--4 of FIG. 2 and in the direction indicated;

FIG. 5 is a gragmentary sectional view through a modified form of jointaccording to the invention;

FIG. 6 is a median sectional view through another modified form of jointconstructed in accordance with the invention;

FIG. 7 is a top plan view, shown with portions broken away, of amodified pipe joint having a gasket interposed between pipe ends beingjoined; and

FIG. 8 is a fragmentary sectional view similar to FIG. 4, taken alongthe line 8-8 of FIG. 7 and in the direction indicated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reference character 10 isused generally to designate a joint constructed in accordance with theinvention and the reference character 12 is used generally to designatea clamp constructed in accordance with the invention. A joint asreferred to herein will mean a pair of pipes which are associatedtogether preparatory to securing the same in such association. It willexclude securing means. When securing means are included, the assemblywill be referred to as a joint with pipe clamp.

The pipe joint 10 is formed of a pair of pipes 14 and 16 which areformed with rolled ends, thereby producing the ring-like bead formations18 and 20 on such ends. The axially facing surfaces comprise annularflanges 22 and 24 which butt to form the contact juncture 26. Thering-like bead formations 18 and 20 (hereinafter called beads) are ofsubstantially greater outer diameter than the pipes 14 and 16 which inthis case are of the same outer diameter. When the joint is assembledthe beads are arranged side by side as shown in FIGS. 1, 2 and 4.

The pipe clamp 12 is formed of two semi-circular bands 28 and 30 eachhaving a medial portion and two ends. The band 28 has the medial portion32, one end which has a generally radially outwardly extending tab ortongue 34 provided with a perforation for receiving the bolt 36, theother end having a generally rectangular bight 38 formed of a firstplanar portion 40, a right angle bent connecting bridge 42 and a secondplanar portion 44 parallel with and spaced from the planar portion 40.The medial portion 32 is formed in a semicircle and has a somewhatarcuate cross section, the concave surface facing radially inward asbest shown in FIG. 4. The sides of the arcuate cross section aredesignated 46 and 48 in this view and these sides present the equivalentof two wedging surfaces to the opposite beads 18 and 20 respectivelyalong a substantial portion of the halves thereof facing the medialportion 32.

The band 30 has the medial portion 50 of identical construction as themedial portion 32 and one end which has a generally radially extendingflat tongue 52 adapted to fit into the bight 38 and engage against theinner face of the planar portion 44, being shorter than said planarportion. The other end of the band 30 has a tab or tongue 54 whichextends generally radially from the band and has a right angle bentflange 56 on its free end which is spaced from the tab or tongue 34 asshown at 58. The tab 54 has a perforation which aligns with theperforation in the tab 34 to receive the bolt 36. A nut 60 and washer 62enable the bolt 36 to be taken up to bring the tabs 34 and 54 toward oneanother, the flange 56 preventing inordinate distortion if the nut 60 isovertightened on the bolt.

Considering the structure as thus far described, reference is made tothe various tabs or tongues as extending radially outward of the clamp12. Actually this is not technically correct since the tongue 34 and theplanar portion 40 lie in a plane which is spaced from the center of theclamp 12. The center of the clamp 12 is also the axis of the pipes 14and 16 and hence the clamp and joint are coaxial as conventional. Thetongue 54 and planar portion 44 also lie in substantially the same planespaced from the center of the clamp 12. These tongues and planarportions will be referred to as substantially radially extending inorder to avoid complex technical description of the actual construction.The spacing between the tongues 34 and 54 must be such as to allow forsome movement toward one another during the taking up of the nut so thatthe clamp 12 may be compressed upon the joint 10. The bight 38 is fairlyopen with the planar portions 40 and 44 spaced well apart so that theclamp 12 may be readily assembled upon the joint. The bolt 36 should belong enough so that the halves of the clamp may be moved apartsufficient to enable them to be placed on the joint after which thetongue 52 is swung into position in the bight as shown. As soon as theinner grooves of the medial sections 32 and 50 commence to engage withthe beads 18 and 20, the tongue 52 will be laterally restrained frommoving out of the bight 38. As the nut 60 is screwed onto the bolt 36bringing the tongues 34 and 54 together, the tongue 44 acts as a hingeand the two halves of the clamp 12 come together applying the wedgingforce previously described axially forcing the two flanges 22 and 24together in a tight contact juncture 26.

Since the clamp 12 is intended for heavy duty, the metal from which thesame is fabricated is of relatively heavy gauge. The bight 38 willnormally not distort in applying the clamp 12 to the joint 10. Theillustrated clamp and joint uses 2 inch outer diameter pipe and thedimensions may be proportionally scaled from this consideration. Theclamp 12 was made out of A; inch cold rolled steel sheet, suitablyformed in a stamping press.

It will be seen that the several problems of achieving an emission freeclamped joint have been solved and likewise problems concerned withmanufacture and installation have also been solved. The clamp 12 issimple, easy to fabricate, and, although made out of two pieces, thepieces are not physically attached to one another. The hingingconnection which is achieved is made without the need for any pins,bolts, or complex formations. It is held in assembly by reason of theselfcentering action of the clamp cross sectional configuration coactingwith the beads 18 and 20. It achieves a tight connection between the twopipes 14 and 16 by means of substantial axial force applied in amechanically advantageous manner using constricting force. Due to thehinging action of the halves of the clamp there is no progressivediminution of radial force around the circumference of the clamp whichis a fault with prior art single bolt clamps.

The joint which has been described is satisfactory for the most part,but considering the problem of mass assembly along a fast-moving line, aworker required to hold the two pipes 14 and 16 end to end may have somedifficulty in being required also to assemble the clamp halves thereon.Accordingly jigs or fixtures might have to be provided for this purpose.Such jigs and fixtures are eliminated by the joints and 90 of FIGS. 5and 6. Indeed such joints are preferred over the joint 10, althoughslightly more material is required in said joints 70 and 90.

The joints 70 and 90 are characterized by the provision of a pilot endon one of the pipes fitting into the other pipe to hold the joint intemporary assembly while the clamp is being installed. In each case thesame kind of clamp is used. In the joint 70, there is a pipe 72 withbead 74 on its end exactly as in the case of the pipes 14 and 16. Thesecond pipe 76 has the bead 78 formed at a location spaced from the freeend of the pipe giving rise to a length 80 that extends beyond the bead78, to the left as viewed in FIG. 5. In this case, the length 80telescopes within the pipe 72 and for that purpose has an exteriordiameter which is sufficient to enable this telescoping action. Thelength 80 would be necked during formation of the bead 78 to the smallerdiameter probably in the same die forming the bead 78. Each of the beads74 and 78 will have an axially facing flange-like portion 82 and 84respectively which abut to provide the juncture 86. The added surfaceengagement of the joint 70 provides additional insurance against leakingof emission.

The joint differs from the joint 70 only in that the pipe 92 and thepipe 94 are not of the same size. The pipe 94 is chosen to have anexternal diameter equal to the inner diameter of the pipe 92 so thatthey will telescope within one another. The bead 96 is formed on the endof the pipe 92 as before and the bead 98 is formed on the pipe 94 spacedfrom the free end of the pipe to provide the length 100 between the bead98 and such free end. In this joint 90, therefore, there is no need fornecking the pilot portion 100 of the pipe 94. In all other respects thejoint 90 and its clamp 12 are the same as in the case of the joint 70and its clamp 12.

To provide a longer lasting pipe system, the pipes thereof can be madeof highly corrosive resistant metal, such as stainless steel. However,stainless steel is very tough. Consequently, it is often difficult toroll the ends of stainless steel pipe to a desired shape and the rolledbead ends of individual pipes are not always uniform. As a result,smooth fitting and tight pipe joints are not always obtained when thejoint and clamp of the present invention are used in systems employingpipes of tough metal. To overcome this problem of mismatched(non-uniform) rolled ends of pipes made of a tough metal, a gasket maybe employed, such as the gasket 106 shown in FIGS. 7 and 8.

As shown in FIGS. 7 and 8, a pipe joint 110 similar to pipe joint 10includes a clamp 112 which secures a pair of pipes 114 and 116 together.Specifically, the pipes 114 and 116 are formed with rolled ends formingring-like bead formations (beads) 118 and 120 on such ends in accordancewith the teachings of the invention. The gasket 106 is interposedbetween axially facing surfaces 123 and 125 on annular flanges 127 and129 formed by the beads 118 and 120 and ensures a tight, emission-freeclamped joint 110 in case the surfaces 123 and 125 are not smooth anduniform. In other re spects, the joint 110 is substantially the same asthe joint 10 shown in FIGS. l-4.

From the foregoing description it will be apparent that obviousmodifications may be made to the clamp and joint of the inventionwithout departing from the spirit or scope of the invention as definedin the appended claims.

What is desired to be secured by Letters Patent of the United States is:

l. A clamped joint for use in internal combustion engine exhaust systemswhich comprises:

A. a joint formed of a pair of pipes, each pipe having a bead formationat an end thereof, the bead formations including respective axiallyfacing flange surfaces and the flange surfaces being substantiallyabutted face to face,

B. a pipe clamp engaged over the bead formations and constrictedthereon, the clamp having radially inwardly facing groove means alongits inner surface with opposite surfaces of the groove means engagingthe bead formations and applying wedging forces on said bead meanscausing the flange surfaces to be forced axially together,

C. the clamp being formed of two generally semicircular halves, eachhalf having a substantially radially outwardly extending tongue on oneend thereof with the tongues spaced apart and having cooperatingfastening means for bringing the tongues together in securing the clampto the joint, each half having a medial section provided with saidgroove means, and the second end of each half having cooperatingformations providing a separable hinge connection thereat,

D. said cooperating formations comprising an open bight on one of saidsecond ends and a tab on the other of said second ends, the tab lying inthe bight engaged against one side of said bight in surface engagementonly,

B. said bight being generally rectangular in configuration and having apair of planar portions spaced apart, one planar portion extendingsubstantially radially outwardly of the clamp and the other beingparallel thereto, a bridge connecting the planar portions, said otherplanar portion having a free end, the said tab extending substantiallyradially outwardly of the clamp and being disposed in facing engagementwith the inside of said other planar portion,

F. said tongues having aligned perforations and said fastening meanscomprising a bolt extending through said perforations generallytangential to said clamp, one of said tongues having a right angle bentflange adapted to limit movement of the tongues toward one another.

2. A clamped joint for use in internal combustion engine exhaust systemswhich comprises:

A. a joint formed of a pair of pipes, each pipe having a bead formationat an end thereof, the bead formations including respective axiallyfacing flange surfaces and the flange surfaces being substantially vabutted face to face,

B. a pipe clamp engaged over the bead formations and constrictedthereon, the clamp having radially inwardly facing groove means alongits inner surface with opposite surfaces of the groove means engagingthe bead formations and applying wedging forces on said bead meanscausing the flange surfaces to be forced axially together,

C. one pipe of said joint having its bead formation spaced from the freeend of said one pipe whereby to form a pilot extension, said pilotextension being telescoped within the other pipe to bring the beadformations together,

D. the clamp being formed of two generally semicircular halves, eachhalf having a substantially radially outwardly extending tongue on oneend thereof with the tongues spaced apart and having cooperatingfastening means for bringing the tongues together in securing the clampto the joint, each half having a medial section provided with saidgroove means, and the second end of each half having cooperatingformations providing a separable hinge connection thereat,

E. said cooperating formations comprising an open bight on one of saidsecond ends and a tab on the other of said second ends, the tab lying inthe bight engaged against one side of said bight in surface engagementonly,

F. said bight being generally rectangular in configuration and having apair of planar portions spaced apart, one planar portion extendingsubstantially radially outwardly of the clamp and the other beingparallel thereto, a bridge connecting the planar portions, said otherplanar portion having a free end, the said tab extending substantiallyradially outwardly of the clamp and being disposed in facing engagementwith the inside of said other planar portion,

G. said tongues having aligned perforations and said fastening meanscomprising a bolt extending through said performations generallytangential to said clamp, one of said tongues having a right angle bentflange adapted to limit movement of the tongues toward one another.

3. A clamp for a pipe joint of the type which has a pair of side by sidebeads adapted to be forced against one another axially, said clampcomprising:

A. a pair of independent generally semi-circular halves,

B. each half having a first end and a second end and a medial sectionbetween the ends, the medial section having a generally arcuatecross-section to form inner groove means adapted to be engaged upon theside by side beads,

C. a generally radially extending tongue on each first end, the tonguesbeing spaced apart and having cooperating fastening means associatedtherewith to bring the tongues together in constricting the clamp,

D. the second ends having cooperating formations providing a separablehinge joint thereat,

E. said cooperating formations comprising an open bight on one of saidsecond ends and a tab on the other of said second ends, the tab lying inthe bight engaged against one side of the bight in surface engagementonly,

F. said bight being generally rectangular in configuration and having apair of planar portions-spaced apart, one planar portion extendingsubstantially radially outwardly of the clamp and the other beingparallel thereto, a bridge connecting the planar portions, said otherplanar portion having a free end, the said tab extending substantiallyradially outwardly of the clamp and being disposed in facing engagementwith the inside of the said other planar portion,

G. one of said tongues having a right angle bent flange directed towardthe other tongue and adapted to limit movement of the tongues toward oneanother.

4. The clamp as claimed in claim 3 in which said tongues have alignedperforations and said fastening means comprise a bolt extending throughsaid perforations generally tangential to said clamp.

5. A clamped joint comprising:

A. a pair of pipes, each pipe having a rolled end forming a beadedformation directly thereon at an end thereof, said beaded formation eachincluding respective axially facing flange surfaces, said flangesurfaces being substantially abutted in face-to-face contact, and

B. a pipe clamp formed of two generally semicircular bands each formedof a single piece and each having a semi-circular medial portion and twoend poritions extending respectively outwardly from said medial portion,the medial portion of each band having an arcuate cross-section andradially outwardly facing groove means along its inner surface withopposite surfaces of said groove means engaging the beaded formation andforming wedge portions tangentially engaging only at one point thesurface of the rolled ends forming said beaded formation to apply awedging force thereto to force the flange surfaces axially together, andfastening means cooperating with said respective end portions of saidtwo semi-circular bands to secure the two semi-circular bands in tightfitting engagement over said band formations.

6. The clamped joint as claimed in claim 5 in which one pipe of thejoint has its bead formation spaced from the free end of said one pipewhereby to form a pilot extension, said pilot extension being telescopedwithin the other pipe to bring the bead formations together.

7. The clamped joint as claimed in claim 6 in which the pipes are of thesame outer and inner diameters and the pilot extension is formed as asmaller diameter neck to enable its outer diameter to engage within theother pipe.

8. The clamped joint as claimed in claim 6 in which the pipe having thepilot extension is of an outer diameter substantially the same as theinner diameter of the other pipe.

9. The clamped joint as claimed in claim 5 in which each saidsemi-circular band has a substantially radially outwardly extendingtongue on one end thereof with the tongues spaced apart and havingcooperating fastening means for bringing the tongues together insecuring the clamp to the joint, each semi-circular band having a medialsection provide with said groove means, and the second end of eachsemi-circular band having cooperating formations providing a separablehinge connection thereat.

10. The clamped joint as claimed in claim 9 in which said cooperatingformations comprise an open bight on one of said second ends and a tabon the other of said second ends, the tab lying in the bight engagedagainst side of said other planar portion.

1. A clamped joint for use in internal combustion engine exhaust systemswhich comprises: A. a joint formed of a pair of pipes, each pipe havinga bead formation at an end thereof, the bead formations includingrespective axially facing flange surfaces and the flange surfaces beingsubstantially abutted face to face, B. a pipe clamp engaged over thebead formations and constricted thereon, the clamp having radiallyinwardly facing groove means along its inner surface with oppositesurfaces of the groove means engaging the bead formations and applyingwedging forces on said bead means causing the flange surfaces to beforced axially together, C. the clamp being formed of two generallysemi-circular halves, each half having a substantially radiallyoutwardly extending tongue on one end thereof with the tongues spacedapart and having cooperating fastening means for bringing the tonguestogether in securing the clamp to the joint, each half having a medialsection provided with said groove means, and the second end of each halfhaving cooperating formations providing a separable hinge connectionthereat, D. said cooperating formations comprising an open bight on oneof said second ends and a tab on the other of said second ends, the tablying in the bight engaged against one side of said bight in surfaceengagement only, E. said bight being generally rectangular inconfiguration and having a pair of planar portions spaced apart, oneplanar portion extending substantially radially outwardly of the clampand the other being parallel thereto, a bridge connecting the planarportions, said other planar portion having a free end, the said tabextending substantially radially outwardly of the clamp and beingdisposed in facing engagement with the inside of said other planarportion, F. said tongues having aligned perforations and said fasteningmeans comprising a bolt extending through said perforations generallytangential to said clamp, one of said tongues having a right angle bentflange adapted to limit movement of the tongues toward one another.
 2. Aclamped joint for use in internal combustion engine exhaust systemswhich comprises: A. a joint formed of a pair of pipes, each pipe havinga bead formation at an end thereof, the bead formations includingrespective axially facing flange surfaces and the flange surfaces beingsubstantially abutted face to face, B. a pipe clamp engaged over thebead formations and constricted thereon, the clamp having radiallyinwardly facing groove means along its inner surface with oppositesurfaces of the groove means engaging the bead formations and applyingwedging forces on said bead means causing the flange surfaces to beforced axially together, C. one pipe of said joint having its beadformation spaced from the free end of said one pipe whereby to form apilot extension, said pilot extension being telescoped within the otherpipe to bring the bead formations together, D. the clamp being formed oftwo generally semi-circular halves, each half having a substantiallyradially outwardly extending tongue on one end thereof with the tonguesspaced apart and having cooperating fastening means for bringing thetongues together in securing the clamp to the joint, each half having amedial section provided with said groove means, and the second end ofeach half having cooperating formations providing a separable hingeconnection thereat, E. said cooperating formations comprising an openbight on one of said second ends and a tab on the other of said secondends, the tab lying in the bight engaged against one side of said bightin surface engagement only, F. said bight being generally rectangular inconfiguration and having a pair of planar portions spaced apart, oneplanar portion extending substantially radially outwardly of the clampand the other being parallel thereto, a bridge connecting the planarportions, said other planar portion having a free end, the said tabextending substantially radially outwardly of the clamp and beingdisposed in facing engagement with the inside of said other planarportion, G. said tongues having aligned perforations and said fasteningmeans comprising a bolt extending through said performations generallytangential to said clamp, one of said tongues having a right angle bentflange adapted to limit movement of the tongues toward one another.
 3. Aclamp for a pipe joint of the type which has a pair of side by sidebeads adapted to be forced against one another axially, said clampcomprising: A. a pair of independent generally semi-circular halves, B.each half having a first end and a second end and a medial sectionbetween the ends, the medial section having a generally arcuatecross-section to form inner groove means adapted to be engaged upon theside by side beads, C. a generally radially extending tongue on eachfirst end, the tongues being spaced apart and having cooperatingfastening means associated therewith to bring the tongues together inconstricting the clamp, D. the second ends having cooperating formationsproviding a separable hinge joint thereat, E. said cooperatingformations comprising an open bight on one of said second ends and a tabon the other of said second ends, the tab lying in the bight engagedagainst one side of the bight in surface engagement only, F. said bightbeing generally rectangular in configuration and having a pair of planarportions spaced apart, one planar portion extending substantiallyradially outwardly of the clamp and the other being parallel thereto, abridge connecting the planar portions, said other planar portion havinga free end, the said tab extending substantially radially outwardly ofthe clamp and being disposed in facing engagement with the inside of thesaid other planar portion, G. one of said tongues having a right anglebent flange directed toward the other tongue and adapted to limitmovement of the tongues toward one another.
 4. The clamp as claimed inclaim 3 in which said tongues have aligned perforations and saidfastening means comprise a bolt extending through said perforationsgenerally tangential to said clamp.
 5. A clamped joint comprising: A. apair of pipes, each pipe having a rolled end forming a beaded formationdirectly thereon at an end thereof, said beaded formation each includingrespective axially facing flange surfaces, said flange surfaces beingsubstantially abutted in face-to-face contact, and B. a pipe clampformed of two generally semi-circular bands each formed of a singlepiece and each having a semi-circular medial portion and two endporitions extending respectively outwardly from said medial portion, themedial portion of each band having an arcuate cross-section and radiallyoutwardly facing groove means along its inner surface with oppositesurfaces of said groove means engaging the beaded formation and formingwedge portions tangentially engaging only at one point the surface ofthe rolled ends forming said beaded formation to apply a wedging forcethereto to force the flange surfaces axially together, and fasteningmeans cooperating with said respective end portions of said twosemi-circular bands to secure the two semi-circular bands in tightfitting engagement over said band formations.
 6. The clamped joint asclaimed in claim 5 in which one pipe of the joint has its bead formationspaced from the free end of said one pipe whereby to form a pilotextension, said pilot extension being telescoped within the other pipeto bring the bead formations together.
 7. The clamped joint as claimedin claim 6 in which the pipes are of the same outer and inner diametersand the pilot extension is formed as a smaller diameter neck to enableits outer diameter to engage within the other pipe.
 8. The clamped jointas claimed in claim 6 in which the pipe having the pilot extension is ofan outer diameter substantially the same as the inner diameter of theother pipe.
 9. The clamped joint as claimed in claim 5 in which eachsaid semi-circular band has a substantially radially outwardly extendingtongue on one end thereof with the tongues spaced apart and havingcooperating fastening means for bringing the tongues together insecuring the clamp to the joint, each semi-circular band having a medialsection provide with said groove means, and the second end of eachsemi-circular band having cooperating formations providing a separablehinge connection thereat.
 10. The clamped joint as claimed in claim 9 inwhich said cooperating formations comprise an open bight on one of saidsecond ends and a tab on the other of said second ends, the tab lying inthe bight engaged against one side of said bight in surface engagementonly.
 11. The clamped joint as claimed in claim 10 in which said bightis generally rectangular in configuration and has a pair of planarportions spaced apart, one planar portion extending substantiallyradially outwardly of the clamp and the other being parallel thereto, abridge connecting the planar portions, said other planar portion havinga free end, the said tab extending substantially radially outwardly ofthe clamp and being disposed in facing engagement with the inside ofsaid other planar portion.